Topic 2 Flashcards
chlorination reason
to kill microorganisms
why is a sample of water potable even though it contains impurities
the impurities are harmless
solid to gas
sublimation
compared to physical changes
chemical changes are hard to reverse
pure
made up of a single compound
you can test for purity by finding the boiling point
if its a substance it wont have one expected value, the mixture will gradually evaporate over a range of temperatures
what can you use to mesure the melting point
metal point apparatus
simple distillation
separating a liquid from a solution
fractional distillation
sepearting many liquids with similar boiling points
diagram
water out, in
simple distillation
the substance with the lowest boiling point will evaporate first, reach the condensing tube and condense as it cools, goes down the tube into the beaker
if boiling points are very similar
multiple rounds of distillation
why are there glass beads in fractional distillation
mobile phase
liquids/ gas can move
imobile phase
solid or very viscous liquid
imobile phase
solid or very viscous liquid
draw a pencil line
the ink form a pen may move up
pencil is insoluble in solvent
value of chemical
distance traveled by solute/ solvent
sea water
very expensive to distill as requires alot of energy
Which row of the table shows these three processes in the order in which they are carried
out?
sedimentation, filtration, chlorinisation
Describe how sedimentation is carried out.
put water in a tank and leave it to settle, impurities fall to the botttom
State what could be changed in the experiment to make the Rf value more accurate.
use longer paper
In this experiment, ink sample Y did not move from the start line.
Explain a change to the experiment that would be needed to separate the dyes in ink
sample Y.
use different solvent to ink will dissolve
The liquid collected in the beaker is known as the
distillate
Describe how a sample of pure, dry sodium chloride crystals can be obtained from the
filtrate.
heat, leave on a radiator, pat dry with a cloth, scrape crystals from container
Explain how the water in sea water separates to produce the pure water in this
apparatus.
use a liebig condencer with col wae so all the water vapour condenses, increased effectiveness of cooling
Name the piece of equipment labelled X in Figure 6.
delivery tube
Explain why it is important that the water used is pure.
ions would interefere results, pure water has no ions
(i) Identify the stationary phase in this experiment.
water in the paper
Give a reason why the spots of the food colourings must be above the level of the
solvent, when the paper is placed in the solvent.
so that the solvent will run through spots
Give the reason why the spot of food colouring V has not moved during the
chromatography experiment.
V is insoluble in this solvent
Explain, by referring to Figure 11, which food colouring contained the greatest number
of soluble, coloured substances.
Z, it has teh most spots
